drivers: usb: device: stm32: fix disconnect-gpios configuration.

For some reason, rather than testing for the presence of
disconnect-gpios in the devicetree, the STM32 USB Device driver was
relying on a hidden Kconfig flag to be set.

This patch removes the Kconfig option completely and simply tests for
the DT property - if it's set, you obviously know what you're doing and
obviously need the pull-up GPIO behaviour.

Signed-off-by: Chris Collins <chris@realsimgear.com>
diff --git a/boards/arm/olimexino_stm32/Kconfig.board b/boards/arm/olimexino_stm32/Kconfig.board
index 163bba9..902efe6 100644
--- a/boards/arm/olimexino_stm32/Kconfig.board
+++ b/boards/arm/olimexino_stm32/Kconfig.board
@@ -6,4 +6,3 @@
 config BOARD_OLIMEXINO_STM32
 	bool "OLIMEXINO-STM32 Development Board"
 	depends on SOC_STM32F103XB
-	select USB_DC_STM32_DISCONN_ENABLE if USB_DEVICE_DRIVER
diff --git a/drivers/usb/device/Kconfig b/drivers/usb/device/Kconfig
index 4b32ff0..ba11aeb 100644
--- a/drivers/usb/device/Kconfig
+++ b/drivers/usb/device/Kconfig
@@ -50,13 +50,6 @@
 	  Enable USB support on the STM32 F0, F1, F2, F3, F4, F7, L0, L4, G4, U5 family of
 	  processors.
 
-config USB_DC_STM32_DISCONN_ENABLE
-	bool
-	depends on USB_DC_STM32
-	help
-	  Say Y if your board uses USB DISCONNECT pin to enable the
-	  pull-up resistor on USB DP.
-
 config USB_DC_SAM0
 	bool "SAM0 series USB Device Controller driver"
 	default y
diff --git a/drivers/usb/device/usb_dc_stm32.c b/drivers/usb/device/usb_dc_stm32.c
index 6854dc8..21f4516 100644
--- a/drivers/usb/device/usb_dc_stm32.c
+++ b/drivers/usb/device/usb_dc_stm32.c
@@ -1099,7 +1099,7 @@
 	}
 }
 
-#if (defined(USB) || defined(USB_DRD_FS)) && defined(CONFIG_USB_DC_STM32_DISCONN_ENABLE)
+#if (defined(USB) || defined(USB_DRD_FS)) && DT_INST_NODE_HAS_PROP(0, disconnect_gpios)
 void HAL_PCDEx_SetConnectionState(PCD_HandleTypeDef *hpcd, uint8_t state)
 {
 	const struct device *usb_disconnect;
@@ -1112,4 +1112,4 @@
 			   DT_GPIO_FLAGS(DT_INST(0, st_stm32_usb), disconnect_gpios) |
 			   (state ? GPIO_OUTPUT_ACTIVE : GPIO_OUTPUT_INACTIVE));
 }
-#endif /* USB && CONFIG_USB_DC_STM32_DISCONN_ENABLE */
+#endif /* USB && DT_INST_NODE_HAS_PROP(0, disconnect_gpios) */